Process and apparatus for cooling internal combustion engines

Abstract

A cooling process for an internal combustion engine comprises the steps of mechanically pumping a boilable liquid coolant having a saturation temperature above about 132° C. at atmospheric pressure from the engine coolant jacket through a radiator and back to the coolant jacket, continuously removing by substantially unrestricted convection through at least one outlet in the highest region of the head portion of the coolant jacket substantially all gases other than those that condense in the coolant jacket, conducting gases from the outlet to a condenser, and returning condensate from the condenser to the coolant jacket. Cooling apparatus comprises a liquid cooling circuit and a vapor discharge and condensation circuit adapted to carry out the process.

I claim: 
     
       1. A process for cooling an internal combustion engine comprising the steps of mechanically pumping a boilable liquid coolant having a saturation temperature above about 132° C. at atmospheric pressure from the engine coolant jacket through a heat exchanger and back to the coolant jacket to provide heat rejection in the heat exchanger such that no vapor is formed in the liquid outside the coolant jacket as a result of the pressure drop induced by the pump and such that the temperature of the coolant within portions of the head portion of the coolant jacket that are in elevation above locations adjacent to combustion chamber domes and exhaust runners is maintained below the saturation temperature of the coolant at the system pressure, continuously removing from the engine coolant jacket by substantially unrestricted convection through at least one outlet leading from the highest region in the head portion of the coolant jacket substantially all gases other than gases that condense within the coolant in the jacket, including vapor formed by localized boiling of the liquid coolant in areas adjacent to combustion chamber domes and exhaust runners, whereby the major part of the head portion of the engine coolant jacket is kept filled with coolant in the liquid state at all times, conducting gases from the outlet to a condenser means that includes a condenser chamber, and returning the condensate from the condenser means to the coolant jacket. 
     
     
       2. The process claimed in claim 1 wherein the coolant consists essentially of at least one substance that is miscible with water and has a vapor pressure substantially less than that of water at any given temperature. 
     
     
       3. The process claimed in claim 2 wherein the substance of the coolant is selected from the group consisting of ethylene glycol, propylene glycol, tetrahydrofurfuryl alcohol, and dipropylene glycol. 
     
     
       4. The process claimed in claim 1 wherein the coolant consists essentially of at least one substance that is substantially immiscible with water and has a vapor pressure substantially less than that of water at any given temperature. 
     
     
       5. The process claimed in claim 4 wherein the substance of the coolant is selected from the group consisting of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, dibutyl isopropanolamine, and 2-butyl octanol. 
     
     
       6. The process claimed in claim 1 wherein liquid coolant is circulated from the bore portion of the engine coolant jacket and returned to the head portion of the coolant jacket. 
     
     
       7. The process claimed in claim 1 wherein the liquid condensate is continuously returned from the condenser chamber to the coolant jacket by gravity. 
     
     
       8. The process claimed in claim 1 and further comprising the steps of conducting gases residing in the highest region of the condenser chamber to a recovery condenser that is vented to atmosphere and is in a location likely to be cooler than that of the condenser chamber for condensation of the condensable gases therein and returning the liquid condensate from the recovery condenser to the condenser chamber. 
     
     
       9. The process claimed in claim 8 and further comprising the steps of blocking the transfer of gases from the condenser chamber to the recovery condenser except when the pressure within the condenser chamber exceeds the pressure within the recovery condenser by a predetermined amount by means of a pressure relief valve placed between the condenser chamber and the recovery condenser, and blocking the transfer of condensate and gases from the recovery condenser to the condenser chamber except when the pressure within the recovery condenser plus any head pressure of the condensate exceeds the pressure within the condenser chamber by a predetermined amount by means of a second pressure relief valve placed between the condenser chamber and the recovery condenser. 
     
     
       10. The process claimed in claim 1 and further comprising the steps of conducting gases residing in the highest region of the condenser chamber through a vent to atmosphere when, and only when, the pressure within the condenser exceeds the ambient pressure by a predetermined amount, and conducting ambient air through the vent into the condenser when, but only when, the ambient pressure exceeds the pressure within the condenser by a predetermined amount. 
     
     
       11. Apparatus for cooling an internal combustion engine comprising a coolant jacket around at least part of each combustion chamber and exhaust runner of the engine and containing a boilable liquid coolant having a saturation temperature above 132° C. at atmospheric pressure, a liquid cooling circuit including a heat exchanger and mechanical pump means for circulating the coolant from the coolant jacket through the heat exchanger and back to the coolant jacket to provide heat rejection in the heat exchanger such that no vapor is formed in the liquid cooling circuit as a result of the pressure drop induced by the pump and such that the temperature of the coolant within portions of the head portion of the coolant jacket that are in elevation above locations adjacent to combustion chamber domes and exhaust runners are maintained below the saturation temperature of the coolant for the system pressure, at least one outlet from the highest region in the coolant jacket adapted to remove and release continuously by substantially unrestricted convection from the coolant jacket substantially all gases, including vapor formed by localized boiling of the liquid coolant in areas adjacent to combustion chamber domes and exhaust runners, other than gases that condense in the coolant within the jacket, whereby the major part of the coolant jacket in areas around combustion chamber domes and exhaust runners is kept filled with coolant in the liquid phase at all times, condenser means including a condenser chamber for receiving the gases removed and released from the coolant jacket through the outlet and condensing condensable constituents thereof, and return means for returning the condensate from the condenser means to the coolant jacket. 
     
     
       12. Apparatus according to claim 11 wherein the coolant consists essentially of at least one substance that is miscible with water and has a vapor pressure substantially less than that of water at any given temperature. 
     
     
       13. Apparatus according to claim 12 wherein the substance of the coolant is selected from the group consisting of ethylene glycol, propylene glycol, tetrahydrofurfuryl alcohol, and dipropylene glycol. 
     
     
       14. Apparatus according to claim 11 wherein the coolant consists essentially of at least one substance that is substantially immiscible with water and has a vapor pressure substantially less than that of water at any given temperature. 
     
     
       15. Apparatus according to claim 14 wherein the substance of the coolant is selected from the group consisting of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, dibutyl isopropanolamine, and 2-butyl octanol. 
     
     
       16. Apparatus according to claim 11 wherein the liquid cooling circuit is adapted to circulate coolant from the block portion of the coolant jacket and return the liquid coolant to the head portion of the coolant jacket. 
     
     
       17. Apparatus according to claim 11 wherein the condenser chamber is located at an elevation higher than that of the outlet from the coolant jacket and the return means returns the condensate from the condenser chamber to the coolant jacket by gravity. 
     
     
       18. Apparatus according to claim 11 wherein the condenser chamber has a vent located in the highest region thereof and remote from the inlet thereto. 
     
     
       19. Apparatus according to claim 18 wherein the condenser means further includes a recovery condenser and a vent pipe connecting the vent of the condenser vessel and the recovery condenser and opening at generally the lowest portion of the recovery condenser, the recovery condenser being vented to atmosphere from the highest region thereof and being located in a location likely to be cooler than that of the condenser chamber, whereby when the pressure in the condenser chamber exceeds the pressure in the recovery condenser, gases residing in the highest region of the condenser chamber are conducted into the recovery condenser for condensaton of condensable gases therein and for venting of non-condensable gases, and condensate and gases that reside within the recovery condenser are conducted from the recovery condenser to the condenser chamber whenever the pressure within the recovery condenser exceeds the pressure within the condenser chamber plus the head pressure of the amount of condensate in the vent pipe. 
     
     
       20. Apparatus according to claim 19 and further comprising first pressure relief valve means located between the condenser chamber and the recovery condenser for blocking the passage of gases from the condenser chamber to the recovery condenser except when the pressure within the condenser chamber exceeds the pressure within the recovery condenser by a predetermined amount and second pressure relief valve means located between the condenser chamber and the recovery condenser for blocking the passage of condensate and gases from the recovery condenser to the condenser chamber except when the pressure within the recovery condenser exceeds the pressure within the condenser chamber plus the head pressure of the condensate in the vent pipe predetermined amount. 
     
     
       21. Apparatus according to claim 18 and further comprising outlet pressure relief valve means located at the vent for blocking the passage of gases from the condenser to atmosphere except when the pressure within the condenser chamber exceeds the ambient pressure by a predetermined amount and inlet pressure relief valve means located at the vent for blocking the passage of ambient air from atmosphere to the condenser chamber except when the ambient pressure exceeds the pressure within the condenser chamber by a predetermined amount.